Preparation of iron or steel for lead and tin coating



ric articles from such influences.

.ramns H. mabpmor new Yon-x, N. Y.

ranram'rrou or IRON on. s'rnnr. roa 'Lnan AND rm coarme.

1 413,343. No lDrawing.

To all whom it may concern:

Be it known that I, JAMES H. Manor, a

of preparing ferric articles to receive-a coating of lead, and tin or their alloys deposited thereon from a moltenbath of metal, the lead being usually preferable.

It is known that lead is most resistant to corrosion from atmospheric influences, furtherefore most desirable for protecting fer- .The means whichv have been heretofore devised for securing a coating of lead on of mercury deposited upon the copper, and

third, a film of lead or other protective. metal deposited upon the mercury.

Each of these films forms a certain barrier against the penetration of water or air through the external coating of lead.

The article is first thoroughly cleansed and then subjected to the three baths which forms a' series of combined films upon its surface. r

The following prescriptions are used in practicing the invention, andit will beunderstood that the chemicals may be used in the proportions named or their equivalent.- The copper sulphate solution contains 10%- of copper sulphate, 10% of ammonium sulphate, of mercuric chloride, and 2% of sulphuric acid and deposits a thin firm coat ing of copper on the 'article.-

'ter. nace fumes, or acids, and such a coating is g the mercuric chloride Specification of iietters Patent. Patented Apl 18, 1922; Application filed l'annaryll, i921. Serial No. 436,599.

striking results,-first, it greatly hastens the j precipitation of the copper upon the article,- se that fifteen seconds immersion 'is s'uflicient to produce the thin cop r coating de-' sired and, secondly, it great y hardens the deposited copper and causes such an adhesion of the same that the depositis not disturbed by ordinary handling. The articles coated with copper are then subjected to a mercuric zinc chloridbath.

The COmPOSitIOH of the mercuric bath is 21}% of mercuric chloride, 2%;% of ammo-- nium chloride, 10% of zinc chloride, and 5% of hydrochloric acid. These ingredients are mixed with The immersion the copper coated'article-in this mercuric chloride bath for fifteen to thirty seconds suflices to cover the copper coating with a film of'metallicmercury.- When such-mercury coated articles i are immersed in the molten lead, the film of The deposit'of metallic mercury forms a COIIlJIIIHOHS film when applied over copper,

and it thus serves as a continuous sup ort the required amount of wafor the lead and makes the adhesion-o the lead coating practically perfect. I I

All the operations required to? practice this invention are of such a simple nature, that ordinarily intelligent labor can be employed' to carry on theoperation commercially; the only apparatus needed being the tanks for the copper sulphate bath and the mercuric chloridebath; and the" invention thus furnishes a process of a simple and inexpensive character;

It is found that the coating of, the articles with copper and. mercury film by the baths described herein, can be efi'ected in much less time than by other ordinary processes,- and 4 the. present invention thus offers a great advantage in coating iron .or steel articles at high speed, as the several steps of the'process operate infrom fifteen to thirty seconds,

and theentire preparation of the'article for immersionin the molten bath occupies littlemore than one minute.

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Wire may therefore be run continuously through the copper depositing bath, through ath, and through the.

tank of molten metal, and the lead coatingeifectively attached to the wire so as to preserve it from corrosion. Q

The deposition of copper is very cheaply and rapidly efiected by the copper sulphate bath containing a proportion of mercuric chloride; as it -IS found-that the prescribed method secures a much more rapid deposition of copper than other chemical solutions or an electro-platingprocess, and secures as hard a deposit as by any other any means.

My several improvements in the chemical bathsby which the articles are fitted trimeceive an adhesive lead coating includes first the dipping of the article into a copper sulphate bath which results in a firm and adherent coating of copper, which has not been possible to secure with other copper sulphate solutions which produce a non-adherent and spongy deposit; and secondly, the use of mercuric chloride and zinc chloride as the basis of a mercury zinc bath, instead of the chemicals heretofore used.

My invention furnishes a more effective and perfect coating than those referred to, for the reason that in the process of coating there are deposited three metallic films upon the article each having an important bearing upon the result.

They are, first, the film of copper, second,

the film ofv mercury, and third, the film of lead or other protective metal.

It will be understood that the processes described and claimed herein are not'only applicable to the coating of iron and steel with lead or tin, but with zinc or any other metal commonly used as a protective coatin for iron or steel articles.

T am'aware that articles have been coated with copper by various processes, with the object of permanently protecting the surface of the article by such copper coating;

but I am not aware that articles of iron or steel have been coated with copper and subsequently with a film of mercury as a preparation for coating the articles with lead and analogous metal.

Having thus set forth the nature of the invention What is claimed herein is:

1. The process of protecting iron or steel articles with an unbroken coating of pro tective metal, which consists in applying three metallic films successively tothe articles, first, afilm of copper, second, a film of mercury, and finally an unbroken film of protective metal.

2. The process of coatingferric articles with lead or its alloys," which consists in the following steps: first, coating the surface of the article with a thin film of copper, second,

immersing the copper coated article in a solution of mercuric zinc chloride and form.- ing a thin film ofmercury upon thearticle, and third, dipping the mercury coated article in a molten bath of protective metal and coating the article therewith.

3. The process of coating ferric articles with lead and tin or theiralloys, which consistsin the following steps: first, immersing Y JAMES H. MADDY, 

